1. Field of the Invention
The present invention relates to the provision of an end stop on a zip fastener.
2. Description of the Related Art
The invention is particularly concerned with zip fasteners having moulded coupling elements and may also be used with fasteners having metallic elements which are crimped in place on the fastener tape edge.
The invention is useful with waterproof fasteners, in particular, waterproof fasteners in which waterproof layers on one surface of the fastener tapes abut one another above the plane of the coupling elements to form a seal which prevents infiltration of water. Such fasteners are described in EP-A-1175842 and EP-A-1057423, for example.
Other types of waterproof fasteners are also known. For example in WO 03/037132 abutting waterproof layers are located in the mid-plane of moulded coupling elements. In JP-P2004-321547A the waterproof layers are brought together with greater force to form a more watertight or airtight seal.
Various methods exist for forming end stops on zip fasteners. We are particularly concerned with forming a closed end stop, in which the fastener tapes are joined at the end of the run of coupling elements, and more particularly a bottom end stop. The invention is also useful for the formation of open end stops, particularly top end stops. The top end stop and the bottom end stop are provided to prevent a slider from coming off the slide fastener when it is reciprocally moved thereon to open and close the slide fastener.
Typically an end stop is formed by crimping a metal staple on to the fastener tapes or tapes. For a bottom end stop, the member may be provided to bridge the two tapes to hold them together. For a top end stop the metallic member may be crimped on to the edge of the tape. Furthermore, a top end stop may be formed at the end of the fastener elements on to the edge of each of the opposed fastener tapes to thus provide open end stops. A gap may be formed in the run of coupling elements to facilitate attachment of the end stop. This may be formed by cutting away the elements, particularly when a continuous coil type coupling element is used, or simply by creating a gap or space between discrete coupling elements as they are moulded or crimped on to the tape edge.
With a continuous coil type coupling element, there have been many attempts to utilise the coupling element itself to form an end stop. These typically involve melting the elements, such as described in GB-A-1270179 to fuse opposed elements in coupled disposition (for a bottom end stop) or to fuse adjacent elements at their upper ends on a tape edge (to form a top end stop). However, this typically results in an unsatisfactory shape to the end stop.